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lugged vs non-lugged frames

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  • jisozaki
    Howdy all, I just joined the group and think it s a great idea. I hope to learn a lot from you all and hopefully be able to contribute a bit myself. I was
    Message 1 of 6 , Apr 1, 2005
      Howdy all,

      I just joined the group and think it's a great idea. I hope to learn a
      lot from you all and hopefully be able to contribute a bit myself.

      I was wondering which is a stronger frame, lugged or non-lugged frames?
    • Forbes Bagatelle-Black
      Howdy and welcome. Thanks for posting! In my experience, there is no practical difference in strength between a lugged and a non-lugged frame, assuming that
      Message 2 of 6 , Apr 1, 2005
        Howdy and welcome. Thanks for posting!

        In my experience, there is no practical difference in strength between
        a lugged and a non-lugged frame, assuming that brazing or welding was
        done competently.

        I've seen many, many failed frames. I've never seen one fail at the
        lug/tig weld point. I did see some tig welded stems from Alpinestars
        fail at the welds, but this was because of improper materials and/or
        welding technique. I also know of a tig-welded titanium fork that
        failed catastrophically at the weld. But the fork was designed
        really, REALLY badly, with 45 degree butt-welds holding the blades to
        a horizontal cross tube. That design was just begging for a failure.
        Who ever came up with it should be banned from designing anything for
        the rest of his/her life.

        I think I'm willing to speculate that there is more room for
        manufacturing errors in a lugged frame. That is to say, you can make
        mistakes in the brazing process, leave voids, etc., and the frame will
        probably hold together just fine. Tig welding is less forgiving.

        I've also experimented with epoxy bonding. This seems to work well,
        but you need to have good control over cure temperatures, bonding
        gaps, etc.

        Just my 2 cents... Others may have divergent but equally valid
        viewpoints.

        Yours,

        Forbes Bagatelle-Black
        Santa Clarita, CA

        --- In Bicycle_Restoration@yahoogroups.com, "jisozaki" <jisozaki@y...>
        wrote:
        >
        > Howdy all,
        >
        > I just joined the group and think it's a great idea. I hope to learn a
        > lot from you all and hopefully be able to contribute a bit myself.
        >
        > I was wondering which is a stronger frame, lugged or non-lugged frames?
      • Perry Arnett
        I broke a frame at the crank housing front tube joint; was riding along, put the pedal at the top of the arc and pushed down with all I had to climb a small
        Message 3 of 6 , Apr 1, 2005
          I broke a frame at the crank housing front tube joint; was riding along, put the pedal at the top of the arc and pushed down with all I had to climb a small hill; it came apart and I landed in the dirt. This frame had no lugs.
           
          I was 12, big for my age, and this was in about 1953.  Fortunately, my dad  was a machinist highly skilled in the brazing art so he fixed it and it never came part after that.
           
          He taught me how to repair the Bendix Coaster brake when I was nine, just after I got my first bike - a used girls bike that was given to me by my girl-cousin for my ninth birthday. Been working on bikes ever since.  Don't ride much any more; the cars'll kill ya.
           
          I think I'd agree with your analysis, Forbes; the key is how well the job was done.
           
          Perry  37 deg, 39' 46" N, 113 deg, 04' 08" W' 5990'
           
           
           
           
           
          ----- Original Message -----
          Sent: Friday, April 01, 2005 12:42 PM
          Subject: [Bicycle_Restoration] Re: lugged vs non-lugged frames


          Howdy and welcome.  Thanks for posting!

          In my experience, there is no practical difference in strength between
          a lugged and a non-lugged frame, assuming that brazing or welding was
          done competently.

          I've seen many, many failed frames.  I've never seen one fail at the
          lug/tig weld point.  I did see some tig welded stems from Alpinestars
          fail at the welds, but this was because of improper materials and/or
          welding technique.  I also know of a tig-welded titanium fork that
          failed catastrophically at the weld.  But the fork was designed
          really, REALLY badly, with 45 degree butt-welds holding the blades to
          a horizontal cross tube.  That design was just begging for a failure.
          Who ever came up with it should be banned from designing anything for
          the rest of his/her life.

          I think I'm willing to speculate that there is more room for
          manufacturing errors in a lugged frame.  That is to say, you can make
          mistakes in the brazing process, leave voids, etc., and the frame will
          probably hold together just fine.  Tig welding is less forgiving.

          I've also experimented with epoxy bonding.  This seems to work well,
          but you need to have good control over cure temperatures, bonding
          gaps, etc.

          Just my 2 cents...  Others may have divergent but equally valid
          viewpoints.

          Yours,

          Forbes Bagatelle-Black
          Santa Clarita, CA

          --- In Bicycle_Restoration@yahoogroups.com, "jisozaki" <jisozaki@y...>
          wrote:
          >
          > Howdy all,
          >
          > I just joined the group and think it's a great idea. I hope to learn a
          > lot from you all and hopefully be able to contribute a bit myself.
          >
          > I was wondering which is a stronger frame, lugged or non-lugged frames?



        • Steve marsala
          I think the standard response is that they are equal in general strength of course you did just open a can of worms.haha. Steve Chicago ...
          Message 4 of 6 , Apr 1, 2005
            I think the standard response is that "they are equal
            in general strength" of course you did just open a
            can of worms.haha.

            Steve
            Chicago


            --- jisozaki <jisozaki@...> wrote:
            >
            > Howdy all,
            >
            > I just joined the group and think it's a great idea.
            > I hope to learn a
            > lot from you all and hopefully be able to contribute
            > a bit myself.
            >
            > I was wondering which is a stronger frame, lugged or
            > non-lugged frames?
            >
            >
            >
            >



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          • beaver_lodge@juno.com
            I broke a lugged frame about an inch above the crank lug. Didn t land in the dirt, but, the bike had a real soft floppy feel til I saw what was the matter.
            Message 5 of 6 , Apr 1, 2005
              I broke a lugged frame about an inch above the crank lug.
              Didn't land in the dirt, but, the bike had a real soft floppy feel
              til I saw what was the matter.
              Going up the same small hill (another year) I sheared off the
              rear axle - solid axle, no quick disconnect - at the chain side.
              Goofy!!
              Jim
               
              On Fri, 1 Apr 2005 13:00:48 -0700 "Perry Arnett" <pjarnett9939@...> writes:
              I broke a frame at the crank housing front tube joint; was riding along, put the pedal at the top of the arc and pushed down with all I had to climb a small hill; it came apart and I landed in the dirt. This frame had no lugs.
               
              I was 12, big for my age, and this was in about 1953.  Fortunately, my dad  was a machinist highly skilled in the brazing art so he fixed it and it never came part after that.
               
              He taught me how to repair the Bendix Coaster brake when I was nine, just after I got my first bike - a used girls bike that was given to me by my girl-cousin for my ninth birthday. Been working on bikes ever since.  Don't ride much any more; the cars'll kill ya.
               
              I think I'd agree with your analysis, Forbes; the key is how well the job was done.
               
              Perry  37 deg, 39' 46" N, 113 deg, 04' 08" W' 5990'
               
               
               
               
               
              ----- Original Message -----
              Sent: Friday, April 01, 2005 12:42 PM
              Subject: [Bicycle_Restoration] Re: lugged vs non-lugged frames


              Howdy and welcome.  Thanks for posting!

              In my experience, there is no practical difference in strength between
              a lugged and a non-lugged frame, assuming that brazing or welding was
              done competently.

              I've seen many, many failed frames.  I've never seen one fail at the
              lug/tig weld point.  I did see some tig welded stems from Alpinestars
              fail at the welds, but this was because of improper materials and/or
              welding technique.  I also know of a tig-welded titanium fork that
              failed catastrophically at the weld.  But the fork was designed
              really, REALLY badly, with 45 degree butt-welds holding the blades to
              a horizontal cross tube.  That design was just begging for a failure.
              Who ever came up with it should be banned from designing anything for
              the rest of his/her life.

              I think I'm willing to speculate that there is more room for
              manufacturing errors in a lugged frame.  That is to say, you can make
              mistakes in the brazing process, leave voids, etc., and the frame will
              probably hold together just fine.  Tig welding is less forgiving.

              I've also experimented with epoxy bonding.  This seems to work well,
              but you need to have good control over cure temperatures, bonding
              gaps, etc.

              Just my 2 cents...  Others may have divergent but equally valid
              viewpoints.

              Yours,

              Forbes Bagatelle-Black
              Santa Clarita, CA

              --- In Bicycle_Restoration@yahoogroups.com, "jisozaki" <jisozaki@y...>
              wrote:
              >
              > Howdy all,
              >
              > I just joined the group and think it's a great idea. I hope to learn a
              > lot from you all and hopefully be able to contribute a bit myself.
              >
              > I was wondering which is a stronger frame, lugged or non-lugged frames?



               
            • Forbes Bagatelle-Black
              I ve seen bikes fail at that point more than once - not as often as failure on the top or down tubes roughly two inches behind the head tube, but a few times
              Message 6 of 6 , Apr 1, 2005
                I've seen bikes fail at that point more than once - not as often as
                failure on the top or down tubes roughly two inches behind the head
                tube, but a few times anyway. That area definitely sees more than its
                fair share of stress, probably because of torque and flex in the
                bottom bracket from cranking on the pedals. I imagine the metal
                fatigues after a couple million flex cycles.

                Yours,

                Forbes B-Black
                Santa Clarita, CA

                --- In Bicycle_Restoration@yahoogroups.com, beaver_lodge@j... wrote:
                > I broke a lugged frame about an inch above the crank lug.
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